Coated article with low-E coating having absorbing layer over functional layer designed to increase outside reflectance

ABSTRACT

A coated article includes a low-E coating having an absorbing layer located over a functional layer (IR reflecting layer) and designed to cause the coating to have an increased outside reflectance (e.g., in an IG window unit) and good selectivity. In certain embodiments, the absorbing layer is metallic, or substantially metallic, and is provided directly over and contacting a lower of two IR reflecting layers. In certain example embodiments, a nitride based layer (e.g., silicon nitride or the like) may be located directly over and contacting the absorbing layer in order to reduce or prevent oxidation thereof during heat treatment (e.g., thermal tempering, heat bending, and/or heat strengthening) thereby permitting predictable coloration, high outside reflectance values, and/or good selectivity to be achieved.

This invention relates to a coated article including a low-E coating. Incertain example embodiments, an absorbing layer of the low-E coating islocated over a functional layer (IR reflecting layer) and is designed tocause the coating to have an increased outside reflectance (e.g., in anIG window unit), and/or increased glass side visible reflectance (e.g.,measured monolithically), and good selectivity. In certain exampleembodiments, the absorbing layer is metallic, or substantially metallic,and is provided directly over and contacting a lower of two IRreflecting layers. In certain example embodiments, a nitride based layer(e.g., silicon nitride or the like) is located directly over andcontacting the absorbing layer in order to reduce or prevent oxidationthereof during heat treatment (e.g., thermal tempering, heat bending,and/or heat strengthening) thereby permitting predictable coloration,high outside reflectance values, and/or good selectivity to be achievedafter the heat treatment. Coated articles according to certain exampleembodiments of this invention may be used in the context of insulatingglass (IG) window units, vehicle windows, other types of windows, or inany other suitable application.

BACKGROUND OF THE INVENTION

Coated articles are known in the art for use in window applications suchas insulating glass (IG) window units, vehicle windows, and/or the like.It is known that in certain instances, it is desirable to heat treat(e.g., thermally temper, heat bend and/or heat strengthen) such coatedarticles for purposes of tempering, bending, or the like in certainexample instances.

In certain situations, designers of coated articles often strive for acombination of high outside reflectance for aesthetic purposes combinedwith good selectivity, desirable visible transmission, low emissivity(or emittance), and low sheet resistance (R_(s)). Low-emissivity (low-E)and low sheet resistance characteristics permit such coated articles toblock significant amounts of IR radiation so as to reduce for exampleundesirable heating of vehicle or building interiors. However, heattreatment of coated articles typically requires use of temperature(s) ofat least 580 degrees C., more preferably of at least about 600 degreesC. and still more preferably of at least 620 degrees C. The use of suchhigh temperatures (e.g., for 5-10 minutes or more) often causes coatingsto break down, have undesirably low outside visible reflectance and/orcauses one or more of the aforesaid desirable characteristics tosignificantly deteriorate in an undesirable manner.

U.S. Patent Document 2005/0202254, commonly owned and herebyincorporated herein by reference, discloses a coated article having thefollowing layers on a glass substrate, from the glass substrateoutwardly.

Layer

-   Glass Substrate-   TiO₂-   Si₃N₄-   ZnO-   Ag-   NiCrO_(x)-   SnO₂-   Si₃N₄-   SnO₂-   ZnO-   Ag-   NiCrO_(x)-   SnO₂-   Si₃N₄

While the aforesaid coated article is heat treatable, and has manydesirable and good characteristics, it does have problems regarding itsundesirably low outside visible reflectance when the coated article isused in an IG window unit. In particular, U.S. 2005/0202254 states thatIG window units having the coating are only able to realize an outsideglass side visible reflectance of 1-12%.

As another example, while the coated article of U.S. Pat. No. 8,017,243has many desirable and good characteristics, it has problems regardingits undesirably low outside or glass side reflective visiblereflectance. In particular, the tables in the '243 patent show that IGwindow units having the coating are only able to realize an outsideglass side visible reflectance of 1-14% (see the RgY values).

As another example, while the coated article of U.S. Pat. No. 7,419,725has many desirable and good characteristics, it has problems regardingits undesirably low outside or glass side reflective visiblereflectance. In particular, Examples 1-2 in the '725 patent show that IGwindow units having the coating are only able to realize an outsideglass side visible reflectance of 16.9 to 17.7% (see the RgY values).

In view of the above, it will be apparent to those skilled in the artthat there exists a need in the art for a coated article with moredesirable optical characteristics (e.g., higher outside glass sidevisible reflectance in an IG window unit combined with low-emissivityand desirable visible transmission).

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

This invention relates to a coated article including a low-E coating. Incertain example embodiments, an absorbing layer of the low-E coating islocated over a functional layer (IR reflecting layer) and is designed tocause the coating to have an increased outside visible reflectance(e.g., in an IG window unit) and/or increased glass side visiblereflectance (e.g., measured monolithically), along with desired visibletransmission, selectivity, a low SHGC, and low emissivity. In certainexample embodiments, the absorbing layer is metallic, or substantiallymetallic, and is provided directly over and contacting a lower of two IRreflecting layers. In certain example embodiments, the metallic orsubstantially metallic absorbing layer (e.g., NiCr) is from about 25-50angstroms (Å) thick. Unexpectedly, this has surprisingly been found toincrease outside visible reflectance in IG window unit applications,and/or increased glass side visible reflectance in when measuredmonolithically, while still permitting desirable visible transmissionand low-emissivity. In certain example embodiments, a nitride basedlayer (e.g., silicon nitride or the like) is located directly over andcontacting the absorbing layer in order to reduce or prevent oxidationthereof during heat treatment (e.g., thermal tempering, heat bending,and/or heat strengthening) thereby permitting predictable coloration,high outside reflectance values, and/or good selectivity to be achievedafter the heat treatment. Coated articles according to certain exampleembodiments of this invention may be used in the context of insulatingglass (IG) window units, vehicle windows, other types of windows, or inany other suitable application.

In certain example embodiments of this invention, there is provided acoated article including a coating supported by a glass substrate, thecoating comprising: first and second infrared (IR) reflecting layerscomprising silver, wherein the first IR reflecting layer is locatedcloser to the glass substrate than is the second IR reflecting layer,and wherein the first IR reflecting layer comprising silver is locatedover and directly contacting a layer comprising zinc oxide; asubstantially metallic absorption layer located over and directlycontacting the first IR reflecting layer; a layer comprising a nitridelocated over and directly contacting the substantially metallicabsorption layer; a layer comprising metal oxide located over the layercomprising the nitride; at least one dielectric layer located over thesecond IR reflecting layer; and wherein the coating has a sheetresistance of less than or equal to 3.0 ohms/square, and the coatedarticle measured monolithically has a visible transmission of from about20-70% and a glass side visible reflectance of at least 20%. In certainexample embodiments the coated article may be heat treated (e.g.,thermally tempered so that the tempering is performed when the coatingis on the glass substrate). In certain example embodiments, the coatedarticle may be provided in an IG window unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a coated article according to anexample embodiment of this invention.

FIG. 2 is a cross section view of an IG unit according to an exampleembodiment of this invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Coated articles herein may be used in applications such as IG windowunits, vehicle windows, monolithic architectural windows, residentialwindows, and/or any other suitable application that includes single ormultiple glass substrates.

In certain example embodiments of this invention, the coating includes adouble-silver stack, although this invention is not so limited in allinstances.

For example, in certain example embodiments of this invention, heattreated (HT) and/or non-HT coated articles having multiple IR reflectinglayers (e.g., two spaced apart silver based layers) are capable ofrealizing a sheet resistance (R_(s)) of less than or equal to 3.0 (morepreferably less than or equal to 2.5, even more preferably less than orequal to 2.0, and most preferably less than or equal to 1.7). In certainexample embodiments, following and/or before heat treatment (HT) and asmeasured in monolithic form, coated articles herein are capable ofrealizing a visible transmission (Ill. C, 2 degree) of from about20-70%, more preferably from about 30-60%, even more preferably fromabout 35-55%, and most preferably from about 40-50%. Moreover, incertain example embodiments (HT or non-HT), when coupled to anotherglass substrate to form an IG window unit, IG window unit coatedarticles according to certain example embodiments of this invention arecapable of realizing a visible transmission of from about 20-70%, morepreferably from about 30-60%, even more preferably from about 35-55%,more preferably from about 40-50%, and most preferably from about41-46%. In certain example embodiments, following and/or before heattreatment (HT) and as measured in monolithic form, the glass sidevisible reflectance (RgY %) is significantly higher (e.g., at leastabout 5% higher, more preferably at least about 10% or 15% higher thanthe film side visible reflectance (RfY %). For example, where 24% is theglass side visible reflectance and 12% is the film side visiblereflectance, the glass side visible reflectance is 12% higher than thefilm side visible reflectance (24%−12%=12%). In certain exampleembodiments of this invention, following and/or before heat treatment(HT) and as measured in monolithic form, coated articles herein arecapable of realizing a glass side visible reflectance (RgY %) of atleast 20%, more preferably from 20-50%, more preferably from about20-40%, more preferably from about 20-35%, even more preferably fromabout 22-35%, and most preferably from about 24-30%. Moreover, incertain example embodiments (HT or non-HT), when coupled to anotherglass substrate to form an IG window unit, IG window unit coatedarticles according to certain example embodiments of this invention arecapable of realizing a glass side visible reflectance (RgY %) of atleast 20%, more preferably from about 20-50%, more preferably from about20-40%, more preferably from about 20-35%, even more preferably fromabout 22-35%, more preferably from about 23-30% or from about 24-29%,and most preferably from about 25-27%). In certain example embodiments,the coating also enables IG units to have an SHGC value of less than0.27, more preferably less than 0.25, and most preferably less than 0.24in combination with any of the embodiments herein.

The terms “heat treatment” and “heat treating” as used herein meanheating the article to a temperature sufficient to achieve thermaltempering, heat bending, and/or heat strengthening of the glassinclusive article. This definition includes, for example, heating acoated article in an oven or furnace at a temperature of least about 580degrees C., more preferably at least about 600 degrees C., for asufficient period to allow tempering, bending, and/or heatstrengthening. In certain instances, the HT may be for at least about 4or 5 minutes. The coated article may or may not be heat treated indifferent embodiments of this invention.

FIG. 1 is a side cross sectional view of a coated article according toan example non-limiting embodiment of this invention. The coated articleincludes substrate 1 (e.g., clear, green, bronze, or blue-green glasssubstrate from about 1.0 to 10.0 mm thick, more preferably from about1.0 mm to 7.0 mm thick, even more preferably from about 5-7 mm thick,with an example thickness being about 6 mm), and low-E coating (or layersystem) 30 provided on the substrate 1 either directly or indirectly.The coating (or layer system) 30 includes, for example: bottomdielectric silicon nitride based and/or inclusive layer 3 which may beSi₃N₄ (which may or may not be doped with other material(s) such asaluminum in certain example instances) of the Si-rich type for hazereduction, or of any other suitable stoichiometry silicon nitride indifferent embodiments of this invention, first lower dielectric contactlayer 7 (which contacts bottom IR reflecting layer 9), first conductiveand preferably metallic infrared (IR) reflecting layer 9, metallic orsubstantially metallic absorbing layer 4 (e.g., of or including NiCr orthe like) which is located over and directly contacts layer IRreflecting layer 9), dielectric silicon nitride based and/or inclusivelayer 14 which is located over and directly contacts the absorbing layer4, tin oxide inclusive based and/or inclusive interlayer 15, secondlower dielectric contact layer 17 (which contacts IR reflecting layer19), second conductive and preferably metallic IR reflecting layer 19,upper contact layer 21 (which contacts IR reflecting layer 19),dielectric layer 23, and finally protective dielectric layer 25. The“contact” layers 7, 17 and 21 each contact at least one IR reflectinglayer (e.g., layer based on Ag). The aforesaid layers 3-25 make up low-E(i.e., low emissivity) coating 30 that is provided on glass or plasticsubstrate 1. In certain example embodiments, there is no dielectric highindex layer (e.g., TiO₂ layer) between the lower IR reflecting layer 9and the glass substrate 1 (“high index layer” meaning a layer having arefractive index n greater than about 2.15).

In certain example embodiments, the problem we have solved is how tocreate a coating that has a high differential between glass sidereflection (RgY) and film side reflection (RfY), including for instanceafter the heat treating (e.g., thermal tempering) process. Typically,with double silver coating designs the difference between the magnitudeof glass side and film visible reflections is low. A high differentialis aesthetically desired for certain markets such as certain portions ofthe commercial market. Thus, in certain example embodiments of thisinvention, coated articles have been designed to have a high, mirrorlike, glass side visible reflection while maintaining a low film sidevisible reflection. While certain single silver coatings have been ableto do this in the past, certain example embodiments of this inventionrelate to a multi-silver coating capable of realizing this. A drawbackof such single silver coatings is that they tend to have a rather highsolar heat gain coefficient (SHGC) of 0.29 and cannot meet the energycode standard of SHGC <0.25 being proposed where high solar loads arecommon. Certain example embodiments of this invention meet the energycode standards by providing a SHGC of approximately 0.23 whilemaintaining the high reflection differential aesthetics discussedherein. In certain example embodiments of this invention, by using ametallic or substantially metallic “absorbing” NiCr layer instead of a“transparent” NiCrOx layer above the lower silver, a high RgY/RfYdifferential after heat treating can be realized. In certain exampleembodiments, in order to avoid significant oxidizing of the NiCr intoNiCrOx above the lower silver during the heating process a nitride layersuch as silicon nitride is deposited directly on top of the absorbingNiCr layer. Furthermore, in certain example embodiments, in order tominimize or reduce transmitted haze and maintain optical propertiesduring heating a small amount of nitrogen (50 mL) may be introduced intothe absorbing layer directly over the lower silver. The nitrogen haslittle impact on the immediate optical properties of the NiCr butenables it to remain metallic or substantially metallic during heating.

In monolithic instances, the coated article includes only one glasssubstrate 1 as illustrated in FIG. 1. However, monolithic coatedarticles herein may be used in devices such as laminated vehiclewindshields, IG window units, and the like. As for IG window units, anIG window unit may include two spaced apart glass substrates. An exampleIG window unit is illustrated and described, for example, in U.S. Pat.No. 7,189,458, the disclosure of which is hereby incorporated herein byreference. An example IG window unit may include, for example, thecoated glass substrate 1 shown in FIG. 1 coupled to another glasssubstrate via spacer(s), sealant(s) or the like, with a gap beingdefined therebetween. This gap between the substrates in IG unitembodiments may in certain instances be filled with a gas such as argon(Ar). An example IG unit may comprise a pair of spaced apart clear glasssubstrates each about 3-7 mm (e.g., 6 mm) thick, one of which is coatedwith a coating 30 herein in certain example instances, where the gapbetween the substrates may be from about 5 to 30 mm, more preferablyfrom about 10 to 20 mm, and most preferably about 12 mm. In certainexample instances, the coating 30 may be provided on the interiorsurface of either substrate facing the gap, however in preferredembodiments the coating 30 is provided on the interior surface of theouter glass substrate 1 as shown in FIG. 2. An example IG window unit isalso shown in FIG. 2 and may include, for example, the coated glasssubstrate 1 shown in FIG. 1 coupled to another glass substrate 2 viaspacer(s), sealant(s) or the like 4 with a gap 6 being definedtherebetween. This gap 6 between the substrates in IG unit embodimentsmay in certain instances be filled with a gas such as argon (Ar). Thegap 6 may or may not be at a pressure less than atmospheric in differentembodiments of this invention.

Still referring to FIG. 2, an example IG unit may comprise a pair ofspaced apart glass substrates (1 and 2) each about 6 mm thick, one ofwhich is coated with a coating 30 herein in certain example instances,where the gap 6 between the substrates may be from about 5 to 30 mm,more preferably from about 10 to 20 mm, and most preferably about 12-16mm. In certain example embodiments, the coating 30 is provided on theinterior surface of the outer glass substrate 1 as shown in FIG. 2(i.e., on surface #2 from the outside), although it may be provided onthe other substrate 2 in alternative embodiments of this invention.

Absorption layer 4 is, in certain example embodiments of this invention,located over and directly contacting the lower IR reflecting layer 9. Incertain example embodiments, the layer 14 located directly over andcontacting the absorption layer 4 is a nitride-based layer and issubstantially or entirely non-oxidized. This is advantageous in that ithelps prevent (or reduce the likelihood of) the absorption layer frombeing oxidized during heat treatment, thereby better allowing theabsorption layer to perform one of its intended functions, in particularabsorbing at least some amount (e.g., at least 5%, more preferably atleast 10%) of visible light. It will be appreciated that if a layerbecomes too oxidized during heat treatment or the like, it no longer canfunction as an adequate absorption layer.

In certain example embodiments of this invention, absorption layer 4 maybe of or include Ni and/or Cr (e.g., NiCr with any suitable ratio ofNi:Cr). In certain example embodiments, it is desired that theabsorption layer 4 comprises from 0-10% oxygen, more preferably from0-5% oxygen, and most preferably from 0-2% oxygen (atomic %). Moreover,from 0-20% nitrogen, more preferably from 1-15% nitrogen, and mostpreferably from 1-10% nitrogen (atomic %) may be provided in theabsorbing layer 4. While NiCr (e.g., possibly nitrided in certainexample embodiments) is a preferred material for the absorption layer 4,it is possible that other materials may instead be used or in additionto Ni and/or Cr. For example, in certain other example embodiments ofthis invention, the absorption layer 4 may be of or include Ni, Cr,NiCrN_(x), CrN, ZrN, or the like. In non-heat treatable embodiments, anyof the aforesaid materials may be used for the absorption/absorbinglayer 4, as well as other materials such as Ti, Zr, NiOx or the like.

The absorbing layer 4 of the low-E coating is designed to cause thecoating and/or coated article (including an IG unit in certainembodiments) to have an increased outside (and/or glass side) visiblereflectance (e.g., in an IG window unit), along with desired visibletransmission, selectivity, a low SHGC, and low emissivity. In certainexample embodiments, the metallic or substantially metallic absorbinglayer (e.g., NiCr) 4 is thinner than upper contact layer 21 and is fromabout 25-80 angstroms, more preferably from about 25-50 angstroms (Å)thick, more preferably from about 30-40 angstroms (Å) thick, and mostpreferably from about 33-37 angstroms (Å) thick (e.g., about 35angstroms thick). Moreover, in certain example embodiments, absorbinglayer 4 is either metallic or only slightly oxided, whereas uppercontact layer 21 is significantly oxided (e.g., at least about 50%oxided). Thus, layer 4 functions as an absorbing layer and surprisinglyresults in outside or glass side reflectance of the coated article beingsignificantly increased, whereas upper contact layer 21 does notfunction as an absorbing layer.

In certain example embodiments, the metallic or substantially metallicabsorbing layer 4 is located directly between and contacting metallic orsubstantially metallic IR reflecting layer 9 and nitride layer 14 inorder to reduce or prevent oxidation of layer 4 during heat treatment(e.g., thermal tempering, heat bending, and/or heat strengthening)thereby permitting reflectance and visible transmission to be achievedfollowing the heat treatment (HT).

Moreover, in certain example embodiments, a metal oxide based and/orinclusive layer 15 of or including tin oxide may be provided between thenitride based layer 14 and the upper infrared (IR) reflecting layer 19and in particular, in certain example embodiments, between and directlycontacting the nitride based layer 14 and the zinc oxide based and/orinclusive contact layer 17. For example, it has been found that the useof such a tin oxide inclusive interlayer 15 results in a coated articlewhich is capable of realizing desired optical characteristics.

Dielectric layers 3, 14 and 25 may be of or include silicon nitride incertain embodiments of this invention. Silicon nitride layers 3, 14 and25 may, among other things, improve heat-treatability of the coatedarticles, e.g., such as thermal tempering or the like. The siliconnitride of these layers may be of the stoichiometric type (i.e., Si₃N₄),or alternatively of the Si-rich type in different embodiments of thisinvention. For example, Si-rich silicon nitride 3 (and/or 14) combinedwith zinc oxide and/or tin oxide under a silver based IR reflectinglayer may permit the silver to be deposited (e.g., via sputtering or thelike) in a manner which causes its sheet resistance to be lessenedcompared to if certain other material(s) were under the silver.Moreover, the presence of free Si in a Si-rich silicon nitride inclusivelayer 3 may allow certain atoms such as sodium (Na) which migrateoutwardly from the glass 1 during HT to be more efficiently stopped bythe Si-rich silicon nitride inclusive layer before they can reach thesilver and damage the same. Thus, it is believed that the Si-richSi_(x)N_(y) can reduce the amount of damage done to the silver layer(s)during HT in certain example embodiments of this invention therebyallowing sheet resistance (R_(s)) to decrease or remain about the samein a satisfactory manner. Moreover, it is believed that the Si-richSi_(x)N_(y) in layer 3 may help reduce the amount of damage (e.g.,oxidation) done to absorbing layer 4 during HT in certain exampleoptional embodiments of this invention. In certain example embodiments,when Si-rich silicon nitride is used in layer 3 and/or 14, the Si-richsilicon nitride layer as deposited may be characterized by Si_(x)N_(y)layer(s), where x/y may be from 0.76 to 1.5, more preferably from 0.8 to1.4, still more preferably from 0.85 to 1.2. Moreover, in certainexample embodiments, before and/or after HT the Si-rich Si_(x)N_(y)layer(s) may have an index of refraction “n” of at least 2.05, morepreferably of at least 2.07, and sometimes at least 2.10 (e.g., 632 nm)(note: stoichiometric Si₃N₄ which may also be used has an index “n” of2.02-2.04). In certain example embodiments, it has surprisingly beenfound that improved thermal stability is especially realizable when theSi-rich Si_(x)N_(y) layer(s) as deposited has an index of refraction “n”of at least 2.10, more preferably of at least 2.20, and most preferablyfrom 2.2 to 2.4.

Any and/or all of the silicon nitride layers discussed herein may bedoped with other materials such as stainless steel or aluminum incertain example embodiments of this invention. For example, any and/orall silicon nitride layers discussed herein (e.g., 3, 14 and/or 25) mayoptionally include from about 0-15% aluminum, more preferably from about1 to 10% aluminum, in certain example embodiments of this invention. Thesilicon nitride may be deposited by sputtering a target of Si or SiAl incertain embodiments of this invention. Oxygen may also be provided incertain instances in one or more of the silicon nitride layers. Becauselayer 14 is provided to protect the absorbing layer 4 from oxidationduring HT, in certain example embodiments, silicon nitride based layer14 is at least about 50 angstroms thinner, more preferably at leastabout 100 angstroms thinner, than one or both of silicon nitride basedlayers 3 and/or 25. In certain example embodiments, silicon nitridebased layer 14 is at least about 100 angstroms thinner than siliconnitride based layer 25 and is at least about 50 angstroms thinner thansilicon nitride based layer 3. While silicon nitride is a preferredmaterial for layers 3, 14 and 25 in certain example embodiments of thisinvention, it will be recognized that other materials instead or inaddition may be used for one or more of these layers in alternativeembodiments of this invention.

Infrared (IR) reflecting layers 9 and 19 are preferably substantially orentirely metallic and/or conductive, and may comprise or consistessentially of silver (Ag), gold, or any other suitable IR reflectingmaterial. IR reflecting layers 9 and 19 help allow the coating to havelow-E and/or good solar control characteristics. The IR reflectinglayers may, however, be slightly oxidized in certain embodiments of thisinvention. In certain example embodiments, the upper IR reflecting layer19 is thicker (e.g., at least about 5 angstroms thicker, more preferablyat least about 10 or 15 angstroms thicker) than the lower IR reflectinglayer 9.

The upper contact layer 21 may be of or include nickel (Ni) oxide,chromium/chrome (Cr) oxide, or a nickel alloy oxide such as nickelchrome oxide (NiCrO_(x)), or other suitable material(s), in certainexample embodiments of this invention. The use of, for example,NiCrO_(x) in layer 21 allows durability to be improved. The NiCrO_(x) oflayer 21 may be fully (or substantially fully) oxidized in certainembodiments of this invention (i.e., fully stoichiometric), or may onlybe partially oxidized. In certain instances, the NiCrO_(x) layer 21 maybe at least about 50% oxidized. Contact layer 21 (e.g., of or includingan oxide of Ni and/or Cr) may or may not be oxidation graded indifferent embodiments of this invention. Oxidation grading means thatthe degree of oxidation in the layer changes in the thickness of thelayer so that for example a contact layer may be graded so as to be lessoxidized at the contact interface with the immediately adjacent IRreflecting layer 19 than at a portion of the contact layer further ormore/most distant from the immediately adjacent IR reflecting layer 19.Contact layer 21 (e.g., of or including an oxide of Ni and/or Cr) may ormay not be continuous in different embodiments of this invention acrosssubstantially the entire IR reflecting layer 19.

Dielectric layer 15 may be of or include tin oxide in certain exampleembodiments of this invention. However, as with other layers herein,other materials may be used in different instances.

Lower contact layers 7 and/or 17 in certain embodiments of thisinvention are of or include zinc oxide (e.g., ZnO). The zinc oxide oflayers 7 and 17 may contain other materials as well such as Al (e.g., toform ZnAlO_(x)) and/or tin. For example, in certain example embodimentsof this invention, one or more of zinc oxide based layers 7, 17 may bedoped with from about 1 to 10% Al, more preferably from about 1 to 5%Al, and most preferably about 1 to 4% Al.

Dielectric layer 23 may be of or include tin oxide in certain exampleembodiments of this invention. Like other layers of the coating, layer23 is optional and need not be provided in certain example embodimentsof this invention. Dielectric layer 25, which may be an overcoat incertain example instances, may be of or include silicon nitride (e.g.,Si₃N₄) or any other suitable material in certain example embodiments ofthis invention. Optionally, other layers (e.g., a layer of or includingzirconium oxide) may be provided above layer 25. Layer 25 is providedfor durability purposes, and to protect the underlying layers duringheat treatment and/or environmental use. In certain example embodiments,layer 25 may have an index of refraction (n) of from about 1.9 to 2.2,more preferably from about 1.95 to 2.05.

Other layer(s) below or above the illustrated coating may also beprovided. Thus, while the layer system or coating 30 is “on” or“supported by” substrate 1 (directly or indirectly), other layer(s) maybe provided therebetween. Thus, for example, the coating of FIG. 1 maybe considered “on” and “supported by” the substrate 1 even if otherlayer(s) are provided between layer 3 and substrate 1. Moreover, certainlayers of the illustrated coating may be removed in certain embodiments,while other non-illustrated layers may be added between the variouslayers in different example embodiments, or the various layer(s) may besplit with other layer(s) added between the split sections in otherembodiments of this invention without departing from the overall spiritof certain embodiments of this invention.

While various thicknesses and materials may be used in layers indifferent embodiments of this invention, example thicknesses andmaterials for the respective sputter-deposited layers on the glasssubstrate 1 in the FIG. 1 embodiment are as follows, from the glasssubstrate outwardly:

Example Materials/Thicknesses; FIG. 1 Embodiment Layer Preferred MoreExample Glass (1-10 mm thick) Range ({acute over (Å)}) Preferred ({acuteover (Å)}) (Å) Si_(x)N_(y) (layer 3) 40-250 Å 50-200 {acute over (Å)}120 Å ZnO_(x) (layer 7) 10-300 Å 40-150 Å 100 Å Ag (layer 9) 90-200 Å130-170 {acute over (Å)} 151 Å NiCr (layer 4) 25-80 Å 30-40 Å 35 ÅSi_(x)N_(y) (layer 14) 20-250 {acute over (Å)} 25-80 Å 43 Å SnO₂ (layer15) 300-950 Å 500-900 Å 750 Å ZnO_(x) (layer 17) 10-300 Å 40-150 Å 100 ÅAg (layer 19) 100-250 {acute over (Å)} 140-200 Å 172 Å NiCrO_(x) (layer21) 20-60 {acute over (Å)} 30-50 {acute over (Å)} 40 Å SnO₂ (layer 23)0-750 Å 40-250 Å 120 Å Si₃N₄ (layer 25) 80-750 Å 100-320 {acute over(Å)} 225 Å

In certain example embodiments of this invention, coated articles hereinmay have the following optical and solar characteristics set forth inTable 2 when measured monolithically (before any optional HT). Therelevant optical characteristics are in accordance with Ill. C 2°, butnote that L* values are Hunter. The sheet resistances (R_(s)) hereintake into account all IR reflecting layers (e.g., silver based layers 9,19).

Optical/Solar Characteristics (Monolithic; pre-HT and/or post-HT)Characteristic General More Preferred Most Preferred Rs (ohms/sq.):<=3.0 <=2.0 <=1.7 RgY: 20-40% 22-35% 24-30% T_(vis): 20-70% 30-60%40-50%

Moreover, in certain example embodiments of this invention, coatedarticles herein which may have been optionally heat treated to an extentsufficient for tempering, and which have been coupled to another glasssubstrate to form an IG unit, may have the following IG unitoptical/solar characteristics. Note that, when the coating 30 is onsurface #2 of the IG window unit as shown in FIG. 2, the outside visiblereflectance of the IG window unit is represented by R_(g)Y in the tablebelow.

Example Optical Features (IG Unit) Characteristic General More PreferredT_(vis) (or TY)(Ill. C. 2°): 30-60% 35-55% a*_(t) (Ill. C. 2°): −15 to−1 −10 to −3 b*_(t) (Ill. C. 2°):  −4 to +8.0  −1 to +4 L* (Ill. C. 2°):58-80 61-74 R_(f)Y (Ill. C., 2 deg.):  9-15% 11-14% a*_(f) (Ill. C. 2°):−10 to +2.0  −4 to −1 b*_(f) (Ill. C. 2°): −14 to +4 −12 to −4 L* (Ill.C. 2°): 30-55 35-47 R_(g)Y (Ill. C., 2 deg.): 20-40% 24-29% a*_(g) (Ill.C. 2°): −12 to +2.0 −10 to −1 b*_(g) (Ill. C. 2°): −10 to +5  −7 to −1L* (Ill. C. 2°): 34-65 40-60 SHGC (surface #2): <=0.27 <=0.25,<=0.24,<=0.23

Moreover, in certain example embodiments the coated article is thermallystable upon heat treatment (e.g., thermal tempering), characterized byhaving a glass side reflective ΔE* value due to HT of no more than about5.0, more preferably no more than about 4.5, when measuredmonolithically.

The following examples are provided for purposes of example only, andare not intended to be limiting unless specifically claimed.

EXAMPLES

The following Example 1 was made via sputtering on 6 mm thick clearglass substrates so as to have the layer stack set forth below. Example1 is according to example embodiments of this invention as shown inFIG. 1. Example 1 had the following layer stack, where the thicknessesare in units of angstroms (Å).

Layer Glass (6 mm thick) Thickness (A) Si_(x)N_(y) (layer 3) 120 ÅZnO_(x) (layer 7) 100 {acute over (Å)} Ag (layer 9) 151 {acute over (Å)}NiCr (layer 4) 35 {acute over (Å)} Si_(x)N_(y) (layer 14) 43 {acute over(Å)} SnO₂ (layer 15) 750 Å ZnO_(x) (layer 17) 100 {acute over (Å)} Ag(layer 19) 172 {acute over (Å)} NiCrO_(x) (layer 21) 40 {acute over (Å)}SnO₂ (layer 23) 120 Å Si₃N₄ (layer 25) 225 {acute over (Å)}

Example 1 was thermally tempered and was calculated to haveapproximately the following characteristics measured monolithicallyfollowing HT.

Characteristic Ex. 1 (HT) T_(vis) (or TY)(Ill. C. 2°): 47.7% a*_(t)(Ill. C. 2°): −4.5 b*_(t) (Ill. C. 2°): 1.0 R_(f)Y (Ill. C., 2 deg.): 7.0% a*_(f) (Ill. C., 2°): −3.0 b*_(f) (Ill. C., 2°): −14.5 R_(g)Y(Ill. C., 2 deg.): 25.0% a*_(g) (Ill. C., 2°): −1.5 b*_(g) (Ill. C.,2°): −6.5 ΔE* (transmissive): <=4.5 ΔE* (glass side reflective): <=4.5

The tempered coated substrate of Example 1 was then coupled to another 6mm clear glass substrate, with a 12 mm air gap therebetween, to form anIG window unit as shown in FIG. 2 and simulated to have approximatelythe following characteristics.

Characteristic Ex. 1 (IG Unit) T_(vis) (or TY)(Ill. C. 2°): 42.7% a*_(t)(Ill. C. 2°): −5.5 b*_(t) (Ill. C. 2°): 1.0 R_(f)Y (Ill. C., 2 deg.):13.0% a*_(f) (Ill. C., 2°): −2.5 b*_(f) (Ill. C., 2°): −8.0 R_(g)Y (Ill.C., 2 deg.):   26% a*_(g) (Ill. C., 2°): −2.0 b*_(g) (Ill. C., 2°): −6.0SHGC (surface #2): 0.23 Transmission Haze (%): <=0.80

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. Any embodiment described herein may or maynot be used in combination with any other embodiment described herein.

1. A coated article including a coating supported by a glass substrate,the coating comprising: a first layer comprising silicon nitridesupported by the glass substrate; a first layer comprising zinc oxidesupported by the glass substrate and located over and directlycontacting the first layer comprising silicon nitride; first and secondinfrared (IR) reflecting layers comprising silver, wherein the first IRreflecting layer is located closer to the glass substrate than is thesecond IR reflecting layer, and wherein the first IR reflecting layercomprising silver is located over and directly contacting the firstlayer comprising zinc oxide; a substantially metallic absorption layercomprising Ni and/or Cr located over and directly contacting the firstIR reflecting layer; a second layer comprising silicon nitride locatedover and directly contacting the substantially metallic absorptionlayer; a layer comprising metal oxide located over and directlycontacting the second layer comprising silicon nitride; a second layercomprising zinc oxide located over the layer comprising metal oxide andlocated under and directly contacting the second IR reflecting layer; atleast one dielectric layer located over the second IR reflecting layer;and wherein the coating has a sheet resistance of less than or equal to3.0 ohms/square, and the coated article measured monolithically has avisible transmission of from about 20-70% and a glass side visiblereflectance of at least 20%, and wherein the glass side visiblereflectance is at least 5% higher than a film side visible reflectanceof the coated article.
 2. The coated article of claim 1, wherein no highindex layer is located between the first IR reflecting layer and theglass substrate.
 3. The coated article of claim 1, wherein the coatedarticle measured monolithically has a visible transmission of from about35-55%.
 4. The coated article of claim 1, wherein the coated articlemeasured monolithically has a glass side visible reflectance of from20-50%.
 5. The coated article of claim 1, wherein the coated articlemeasured monolithically has a glass side visible reflectance of from20-35%.
 6. The coated article of claim 1, wherein the coated articlemeasured monolithically has a glass side visible reflectance of from24-30%.
 7. The coated article of claim 1, wherein the substantiallymetallic absorption layer has a thickness of from about 25-50 angstroms.8. The coated article of claim 1, wherein the coated article has avisible transmission of from about 30-60%.
 9. The coated article ofclaim 1, wherein the coated article has a visible transmission of fromabout 35-45%.
 10. The coated article of claim 1, wherein said absorptionlayer consists essentially of NiCr.
 11. The coated article of claim 1,wherein the coated article is heat treated.
 12. The coated article ofclaim 1, wherein coated article is thermally tempered and has a glassside reflective AE* value of less than or equal to 4.5 due to thetempering.
 13. The coated article of claim 1, wherein the second layercomprising silicon nitride is at least about 50 angstroms thinner thanthe first layer comprising silicon nitride.
 14. The coated article ofclaim 1, wherein said metal oxide is tin oxide.
 15. The coated articleof claim 1, wherein said at least one dielectric layer located over thesecond IR reflecting layer comprising a third layer comprising siliconnitride.
 16. The coated article of claim 15, wherein the second layercomprising silicon nitride is at least about 100 angstroms thinner thanthe third layer comprising silicon nitride.
 17. The coated article ofclaim 1, wherein the second layer comprising zinc oxide directlycontacts the layer comprising metal oxide.
 18. An insulating glass (IG)window unit comprising said coated article of claim 1 coupled to anotherglass substrate with a space being provided therebetween.
 19. The IGwindow unit of claim 18, wherein the coating is located on an interiorsurface of the glass substrate closest to the sun, and wherein the IGwindow unit has an outside visible reflectance of from 23-30% and anSHGC of less than 0.25.
 20. A coated article including a coatingsupported by a glass substrate, the coating comprising: first and secondinfrared (IR) reflecting layers comprising silver, wherein the first IRreflecting layer is located closer to the glass substrate than is thesecond IR reflecting layer, and wherein the first IR reflecting layercomprising silver is located over and directly contacting a layercomprising zinc oxide; a substantially metallic absorption layer locatedover and directly contacting the first IR reflecting layer; a layercomprising a nitride located over and directly contacting thesubstantially metallic absorption layer; a layer comprising metal oxidelocated over the layer comprising the nitride; at least one dielectriclayer located over the second IR reflecting layer; and wherein thecoating has a sheet resistance of less than or equal to 3.0 ohms/square,and the coated article measured monolithically has a visibletransmission of from about 20-70% and a glass side visible reflectanceof at least 20%.
 21. The coated article of claim 20, wherein no highindex layer is located between the first IR reflecting layer and theglass substrate.
 22. The coated article of claim 20, wherein the coatedarticle measured monolithically has a glass side visible reflectance offrom 24-30%.
 23. The coated article of claim 20, wherein thesubstantially metallic absorption layer has a thickness of from about25-50 angstroms.
 24. The coated article of claim 20, wherein saidabsorption layer comprises a nitride of NiCr.
 25. The coated article ofclaim 20, wherein said absorption layer comprises NiCr.
 26. The coatedarticle of claim 20, wherein coated article is thermally tempered andhas a glass side reflective ΔE* value of less than or equal to 4.5 dueto the tempering.
 27. The coated article of claim 20, wherein the glassside visible reflectance is at least 5% higher than a film side visiblereflectance of the coated article.
 28. The coated article of claim 20,wherein the glass side visible reflectance is at least 10% higher than afilm side visible reflectance of the coated article.
 29. The coatedarticle of claim 20, wherein the glass side visible reflectance is atleast 15% higher than a film side visible reflectance of the coatedarticle.